What you were expecting to happen, and what actually happened:
You can see what happens in the video to someone in my guild. He wasn’t doing anything out of the ordinary. This was during Guild Wars battle.

How often does this happen? When did it begin happening?
Once-off, I suppose? I’ve never seen it.

Thanks, I’ve made a note of this for the future. I’m sorry this happened, but hopefully, it’s just a once off. If it happens again or someone else experiences it please let us know. Please check your in-game mail @Reyas. Unfortunately we can’t restore Guild War scores.